title: Brain structural change and gait decline: a longitudinal population-based study.
abstract: OBJECTIVE
  To investigate longitudinal associations between changes in brain structure and gait decline.
  
  
  METHODS
  Longitudinal.
  
  
  METHODS
  Population-based Tasmanian Study of Cognition and Gait.
  
  
  METHODS
  Two hundred twenty-five individuals aged 60 to 86 (mean age 71.4 ± 6.8) randomly selected from the electoral roll with baseline and follow-up data.
  
  
  METHODS
  Volumes of gray matter, white matter, hippocampi, and white matter lesions (WML) were estimated using automated segmentation from magnetic resonance imaging (MRI). Gait variables were measured using a computerized walkway. Linear regression was used to estimate the association between change in brain MRI measures and change in gait. Time between measurements, age, sex, BMI, education level, total intracranial volume, baseline infarcts, and medical history were used as baseline covariates.
  
  
  RESULTS
  Mean follow-up was 30.6 months. White matter atrophy was associated with a decline in gait speed (P = .001), step length (P = .005), and cadence (P = .001). WML progression was associated with a decline in gait speed (P = .04), and its association with decline in step length was stronger with greater baseline age (P for interaction = .04). Hippocampal atrophy was associated with a decline in gait speed (P = .006) and step length (P = .001). Total gray matter atrophy was associated with decline in cadence in those with cerebral infarcts (P for interaction = .02).
  
  
  CONCLUSIONS
  These are the first longitudinal data demonstrating the relative contributions of brain atrophy and WML progression to gait decline in older people. Effect modification according to age and infarcts suggests a contribution of reduced physiological and brain reserve. Interventions targeting brain health may be important in preventing mobility decline in older people.
authors.affiliation: Stroke and Aging Research Group, Department of Medicine, Southern Clinical School, Monash University, Clayton, Victoria, Australia. michele.callisaya@monash.edu
authors.forename: Michele L
authors.initials: ML
authors.lastname: Callisaya
authors.forename: Richard
authors.initials: R
authors.lastname: Beare
authors.forename: Thanh G
authors.initials: TG
authors.lastname: Phan
authors.forename: Leigh
authors.initials: L
authors.lastname: Blizzard
authors.forename: Amanda G
authors.initials: AG
authors.lastname: Thrift
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
authors.forename: Velandai K
authors.initials: VK
authors.lastname: Srikanth
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D001284:Atrophy / Q000473:pathology; D001921:Brain / Q000473:pathology*; D004185:Disability Evaluation; D018450:Disease Progression; D005260:Female; D020233:Gait Disorders, Neurologic / Q000503:physiopathology*; D015577:Geriatric Assessment; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D018709:Statistics, Nonparametric
keywords: aging; brain structure; gait